1. Field of the Invention
This invention relates generally to AC-DC adapters, and more particularly to controlling energy consumption by AC-DC adapters.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
External AC-DC adapters or power supplies are commonly employed to convert alternating current (AC) wall current to direct current (DC) for powering DC-powered devices, including DC-powered information handling systems such as notebook computers. AC-DC adapters are commonly left connected to wall current power sources even when not connected to a DC-powered device or when connected to a DC-powered device that is not drawing current. Under such conditions, a typical AC-DC adapter remains on and consumes energy. To minimize wasted energy under such adapter operating conditions, current Tier 2 “ENERGY STAR” program requirements specify a maximum no load AC power consumption of less than or equal to 0.5 watts for an external power supply having a nameplate output power rating of less than 10 watts. Most conventional AC-DC power supplies meet this maximum no load AC power consumption requirement by running in a reduced frequency “burst mode.” However, during such a conventional burst mode, the power supply output remains on, and the burst frequency can cause audible issues.